Technical Field
The present invention relates to strategies for enabling full duplex wireless systems. More particularly, the present disclosure is related to using interference alignment for enabling duplex wireless systems and/or enabling full duplex wireless systems using half duplex clients.
Description of the Related Art
In order to increase the spectral efficiency in wireless communication systems, several improvements have been performed in the past decades. Besides having better coding and modulation schemes, using feedback, and multiuser interference cancellation, the most notable strategy has been the use of multiple antenna systems. Multiple input multiple output (MIMO) systems can generate a more reliable channel through diversity in transmitting the signal in multiple channels between the transmit and receive antennas, where each channel goes through a different path and potentially has independent fading or moderate to low correlation to other signal paths. The use of MIMO has shown to increase the capacity as well, where multiple signal streams are transmitted in different spatial dimension of the channel. Nonetheless, increasing the number of antennas results in more complicated demodulation, and decoding scheme that is very hard to achieve the optimal performance in practical systems. Hence, the practical use of multi stream transmission is limited to maximum of two streams in current standards (for example release 12 LTE and all prior releases). More transmit and receive antennas can be used for precoding or beam forming, e.g., up to 4 antennas in release 9 LTE and 8 antennas in release 11 LTE. Yet, increasing the number of antennas increases the hardware complexity and cost, and each antenna requires a separate transmit and receive RF chains.